HV Exit Exam • Set 5 Question 19 of 30
Dielectric insulating mineral oils in transformers and switchgear are generally operated up to continuous voltage stresses of approximately:
✓
Direct Answer
Option C: 50 kV/cm
Standard transformer insulating oils have a breakdown strength of 30 to 60 kV across a standard 2.5 mm test gap (~120–240 kV/cm), operating safely under design working stresses up to ~50 kV/cm.
All Options
A
500 V/cm
B
5 kV/cm
C
50 kV/cm
(Correct Answer)
D
500 kV/cm
Detailed Explanation & Context
Standard transformer insulating oils have a breakdown strength of 30 to 60 kV across a standard 2.5 mm test gap (~120–240 kV/cm), operating safely under design working stresses up to ~50 kV/cm.
Relevant Framework: STCW 2010 Manila Amendments • DG Shipping E-Learning & Exit Exam Standards • High Voltage Safety Officer & Switchgear Operations (HV).
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